Heptasartorite is an extremely rare thallium-lead sulfosalt found almost exclusively in the famous Lengenbach Quarry in Switzerland. It typically occurs as small, lead-grey, heavily striated prismatic crystals associated with other complex sulfosalts in dolomite. Due to its extreme rarity and toxicity, it is sought primarily by advanced systematic mineral collectors.
Is this heptasartorite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch heptasartorite with a known reference. Heptasartorite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Heptasartorite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Heptasartorite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: striated prismatic crystals.
Often confused with
Heptasartorite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside heptasartorite
Minerals reported to co-occur with heptasartorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Tl₇Pb₂₂As₅₅S₁₀₈
- Mohs hardness
- 3
- Density
- 5.32 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Striated Prismatic Crystals
- Cleavage
- Distinct On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Dolomitic Marble of The Lengenbach Deposit
- Typical price
- $100-500+ per thumbnail specimen
Where rockhounds find heptasartorite
Classic worldwide localities
- Lengenbach Quarry, Binntal, Switzerland
Field-hunting tip
Look in dolomitic marble of the lengenbach deposit country — that is the host setting where heptasartorite typically forms. If you start seeing realgar, orpiment, pyrite in float, you are in the right ground. Field specimens usually show a striated prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify heptasartorite?+
Where is heptasartorite found?+
How much is heptasartorite worth?+
Is heptasartorite safe to handle?+
What rocks look like heptasartorite?+
What minerals are found with heptasartorite?+
What kind of rock does heptasartorite form in?+
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Find heptasartorite on the map
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